Difference-based updating of map information is known which updates past map information to current map information (new map information) by receiving a difference between the past map information and the current map information (a change from the past map information to the current map information) and adding the details of the difference to the past map information.
Various techniques have been proposed which relates to the difference-based updating of map information and the extraction of differences between the past map information and the current map information as update data. For example, in Patent Document 1 is disclosed a technique of reducing the size of the update data by confining a target area of updating map information within an area such as a destination and an area on a route.